Method of protecting a surface in a gasifier

Abstract

The method of protecting a surface in a gasifier which is normally an exposed surface in the gasifier. The method includes forming a refractory attachment with a securement surface that confronts the protectable surface in the gasifier and mechanically securing the refractory attachment onto the protectable surface in the gasifier without the refractory attachment penetrating the protectable surface. Such mechanical securing is achieved by providing a latch which if formed of complementary shapes of the securement surface and the protectable surface.

Description

This invention is directed to gasifiers for processing carbonaceous fuels and more particularly to a novel protective refractory shield that is mechanically secured against a protectable surface of the gasifier.The processing of carbonaceous fuels, including coal, oil and gas to produce gaseous mixtures of hydrogen and carbon monoxide, such as coal gas, synthesis gas, reducing gas or fuel gas is generally carried out in a high temperature environment of a partial oxidation gasifier with operating temperatures of approximately 2400.degree. F. to 3000.degree. F. Partial oxidation gasifiers, an example of which is shown in U.S. Pat. No. 2,809,104, are operable with an annulus type fuel injector nozzle for introducing pumpable slurries of carbonaceous fuel feed components into a reaction chamber of the gasifer along with oxygen containing gases for partial oxidation. The annulus type fuel injector nozzle, which is a well known structure, is generally formed of metal such as super alloy ...

AI Technical Summary

Benefits of technology

The latching means for securing the attachment to the protectable surface includes a wedge-shaped or "T"-shaped formation in cross-section that projects from the protectable surface. The term "T"-shaped as used hereinafter is intended to encompass both wedge-shaped and "T"-shaped formations. The "T"-shaped formation has a generally circular path with a predetermined discontinuity such that the "T"-shaped formation has free and portions. The latching means further include a latch recess of "T"-shaped cross-section complementary with the "T"-shaped formation on the protectable surface. The refractory attachment is mountable to the protectable surface by engaging the latch recess of each attachment member with a free end of the "T"-shaped formation and sequentially loading the attachment members onto the "T"-shaped formation until the "T"-shaped formation has been fully loaded. The discontinuity in the "T"-shaped formation is then partially filled by adding an extension to the "T"-shaped formation. An attachment member of smaller size than the previous attachment members is then loaded onto the "T"-shaped formation. The previously loaded attachment members are slid along the "T"-shaped formation until an attachment member bridges the partially filled discontinuity. The attachment members, which necklace the "T"-shaped formation, are locked in position to prevent sliding of the attachment members on the "T"-shaped formation.

Problems solved by technology

The reaction zone is generally the highest thermal gradient zone in the gasifier and the temperature conditions at the reaction zone can cause thermal induced fatigue cracking at the outlet orifice of the fuel injector nozzle.

Because the outlet orifice of the fuel injector nozzle is exposed to corrosive gases and corrosive slag while operating at the extreme temperature conditions previously described, it is particularly vulnerable to breakdown caused by heat corrosion, thermal induced fatigue cracking and chemical deterioration, also referred to as thermal damage and thermal chemical degradation.

Once there is a breakdown of the fuel injector nozzle shut down of a gasifier is unavoidable because the gasification process cannot be carried out until repair or replacement of the fuel injector nozzle is accomplished.

Any shutdown of an operating gasifier is costly because of the termination of synthesis gas ("syngas") production which is normally continuous when the gasifier is in operation.

In a typical gasifier 8 hours downtime translates into a significant loss of syngas production.

Since the fuel ejector nozzle is one of the most vulnerable components in the gasifier and operational shutdowns attributable to fuel injector nozzle repair and replacement generally result in substantial losses of syngas production there have been ongoing efforts to extend the operating life of the fuel injector nozzle.

However, the bonding material is subject to substantially the same temperature conditions as an unprotected fuel injector nozzle and is thus vulnerable to thermal damage and consequential thermal chemical degradation which can cause failure of the bonding material.

Failure of the bonding material will permit the thermal shield to fall away from the outlet end of the fuel injector nozzle, thereby directly exposing the outlet end to the corrosive and thermally damaging ambient conditions in the gasifier.

In addition, the dovetail projection on the ceramic platelets have a narrow support neck that is likely to be an area of weakness or breakage.

Breakage of the support neck can cause the ceramic platelets to fall away from the end surface of the fuel injector nozzle.

Because the quench ring can be exposed to the molten slag and corrosive gases at temperatures of approximately 1800.degree. F. to 2800.degree. F. it is vulnerable to thermal damage and thermal chemical degradation, especially at the downwardly directed surfaces that surround the dip tube.

If the downwardly directed surfaces of a quench ring are thermal shielded with a bonded refractory material, high temperature degradation of the bonding material is likely to occur resulting in fall off of the refractory material from the protectable surface.

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